Fan blade coupling



Oct. 13, 1959 Filed June 19, 1956 M. PETTY 2,908,335

FAN BLADE COUPLING 2 Sheets-Sheet 1 Macon Pe z z 5/ INVENTOR.

wg I 63% M. PETTY FAN BLADE COUPLING Oct. 13, 1959 2 Sheets-Sheet 2Filed June 19, 1956 M0 0 0/7 Fe 2 (5 INVENTOR United States PatentOfiiice 2,908,335 Patented Oct. 13, 1959 2,908,335 FAN BLADE COUPLINGMacon Petty, Houston, Tex., assignor to Hudson Engn i ering Corporation,Houston, Tex., a corporation cxas Application June 19, 1956, Serial No.592,349

7 Claims. (Cl. 170-173) This invention relates to apparatus for couplingfan blades to hubs. In one of its aspects, this invention relates toapparatus of this type which is an improvement over that disclosed andclaimed in my earlier copending application, Serial No. 464,963, filedOctober 27, 1954, and entitled F an Blade Coupling.

As in my earlier application, it is an object of the present inventionto provide apparatus which permits the blade to be adjusted to a desiredpitch and then securely coupled to the hub while maintaining such pitch.

-It is a further object, however, to provide a fan blade coupling havinga housing for receiving the blade shank which is of less expensiveconstruction than the housing of my earlier invention in that itrequires no machining of tapers.

Another object is to provide apparatus including a coupling whichenables the blade to be inserted within and removed from the housingthereof without dismantling either the housing or the fan ring whichconventionally closely surrounds the tip of the blade.

Other and further objects of this invention will appear as thedescription proceeds.

In the accompanying drawings forming a part of the instant specificationand wherein like reference numerals are used in the various views toindicate like parts:

Fig. 1 is an elevational view of a pair of fan blades coupled to arotatable hub, in accordance with the present invention, and closelysurrounded at their outer tip ends by a fan ring, with the leftmostblade in the process of either being inserted within or removed from thehousing of its coupling;

Fig. 2 is an enlarged sectional view of part of the fan of Fig. 1,showing in more detail the novel coupling apparatus thereof;

Fig. 3 is a cross-sectional view of the coupling apparatus, takensubstantially along broken line 3-3 of Fig. 2;

Fig. 4 is a sectional view, taken similarly to Fig. 2, of a slightlymodified form of the novel coupling apparatus of the present invention;

Fig. 5 is a cross-sectional view of the form of coupling apparatus ofFig. 4, taken substantially along broken line 55 of Fig. 4; and

Fig. 6 is a partial sectional view of a still further modified form ofthe invention.

Referring now particularly to Fig. 1 of the drawings, there is shown inFig. 1 a hub 10 rotatable with a shaft 11 disposed centrally within anannular fan ring 12. A pair of fan blades 13 are coupled to the hub bymeans of one form of the apparatus of the present invention, whichincludes a shank 13a on the inner end of each blade received within aclamp 14 attached to the hub. The outer tip ends of the blades areclosely surrounded by the ring 12 so that they canot be moved radiallyof the hub or axially of the clamp a distance suflicient to permit theirshanks to be inserted within or removed from the clamps withoutdismantling either or both of the clamp and the fan ring. As will beapparent from the description to follow, however, the coupling apparatusof the present invention is so constructed as to permit the fan blade 13to be tilted with respect to the axis of the clamp '14, as shown by theleftmost blade in Figs. 1 and 2, so that its shank 1311 may be insertedwithin or removed from the clamp without such dismantling.

As shown in Fig. 2, the hub 10 comprises a cup-shaped member 1 5 open atone end and provided at its opposite end with an inwardly disposed boss16 having a socket 17 fixedly secured therein for receiving the shaft1'1 (removed from Fig. 2). An annular space 18 between the innerperiphery of the cup 15 and the boss 16 permits I access to the means ofattaching each clamp 14 to the hub.

Each clamp 14 comprises a housing 19 having rear wall 20 and an opening21 therein opposite the rear wall for receiving the shank 13a of theblade. Each housing is attached to the hub 10 with the axis of itsopening 21 extending radially thereof by means of a bolt 22 receivedthrough aligned openings 23 and 24 in the rear wall 20 of the housingand the cup 15 of the hub, respectively. More particularly, each housingis spaced from the cup 15 by a spacer 25 disposed therebetween andhaving an opening' 26 therethrough receiving an intermediate length ofbolt 22. As shown in Fig. 2, the head of each bolt bears against awasher 27 held against the inside of the rear wall 20 of the housing,and a nut 28 is received over the threaded end of the bolt for hearingagainst a similar washer 27 held against the inner periphery of the cupwithin annular space '18. Each of the washers and spacer may be slottedto receive a lock pin 29 for the nut and bolt. I

The opening 21 in the housing is cylindrical and of such diameter as topermit the blade shank 13a to be inserted therein and removed therefrom,in a manner to be described hereinafter. The opening 21 is also providedwith a groove 30 about its inner periphery within which a retainerelement is adapted to be disposed in position for engagement by ashoulder 31 about the blade shank in a manner to maintain the bladeagainst rotation within the housing. More particularly, the shoulder 31faces away from the rear wall 20 of the housing and the groove 30 isadapted to receive separate curved portions 32 of the retainer elementhaving parts which project radially inwardly of the periphery of theopening when so received, so that the shank of the blade may be moved,by force transmitting means to be described hereinafter, in a directionaxially of the opening and away from the rear wall and into abutmentabout its shoulder 31 with the inwardly projecting parts. On the otherhand, the means for so moving the blade shank may be relieved orretracted in such a manner that the shoulder on the blade shank issufficiently free from the retainer element so that the blade can berotated to a desired pitch or, if desired, the afore-mentioned parts ofthe retainer element may be removed from inwardly projecting relationwithin the housing opening to permit removal of the blade shanktherefrom, in a manner to be described.

It will be noted from the foregoing that, in accordance with a novelaspect of the present invention, the cylindrical opening in the housingobviates the necessity of machining a taper therein, as was the case inmy earlier invention. Furthermore, in providing an arrangement whichpermits insertion and removal of the fan blade without dismantling ofthe housing, the novel coupling apparatus of the present inventionenables such housing to be fabricated as an integral part.

As previously mentioned, the retainer element parts are removable frominwardly projecting relation within housing opening $20. In a preferredform, such removal is accomplishedby removal of the portions 32 from the3 housing, as illustrated in Fig. 2 and in a manner to be describedhereinafter.

As can be seen from Fig. 2, that portion 33 of the blade shank 13abetween shoulder 31 and the end thereof is tapered or, morespecifically, conically shaped convergently way from the shoulder. Thus,with the force transmitting means retracted and the retainer elementparts removed, the blade may be tilted with respect to the axis ofhousing opening 21 to such a position as to permit it to be movedinwardly or outwardly past the fan ring 12 without dismantling same.That is, as illustrated by the leftmost blade 13 of Figs. 1 and 2, theblade may be tilted to such a position that its outer tip end will beclear of the open end of the fan ring, while, at the same time, itsshank is free to be inserted within or removed from the housing 19. Thelength of the tapered portion 33 of the blade shank is shorter than thelength of opening 21 between the rear wall 20 and the groove 32 topermit the shank to be cocked in the manner illustrated in Fig. 2, aswell as to permit the shoulder 31 of the blade shank to be moved intoand out of fixed engagement with respect to the retainer elementportions 32.

The portion of the blade shank 13a on the side of shoulder 31 oppositefrom the end of the shank is substantially cylindrical for a suflicientlength to permit the portions 32 to be moved through the end of theopening within an annular space between this cylindrical portion of theblade shank and the opening 21 in the housing 19. The retainer elementportions 32 are spaced circumferentially apart, as best shown in Fig. 5,so that with the blade shank shoulder 3'1 free of the portions, they maybe individually removed, as by prying with a suitable tool (not shown),from a position within groove 30 to a position removed from the housing.Obviously, the portions may be forced into place by a reversal of suchprocedure. Also, as illustrated in Fig. 2, tilting of the blade mayfacilitate removal or insertion of the portion (in this case, thelowermost portion). In this preferred form of the invention, theportions are tubular or circular in cross section and the groove 30 isarcuate or curved to accommodate the outer periphery thereof when theportions are disposed within the grooves.

In the modified form of coupling apparatus shown in Fig. 6, the retainerelement portions 34 are tapered along their inner surfaces 35convergently toward the open end of the housing for wedging engagementwith a similarly tapered shoulder 35a on the blade shank 13a. As in thecase of the tubular retainer element portions 32, the tapered portions34 are circumferentially spaced apart and removably disposable withingrooves 36 of any suitable cross-section. It will be understood that thetapered surfaces 35 on the portions 34 provide a large bearing surfacefor resisting the centrifugal force of the blades during rotation.

Along this same line, it can be seen from the modified form of couplingapparatus shown in Fig. 4 that the shoulder 37 on the blade shank 13amay be provided with a recessed portion 37a curved to substantially theradius of the retainer portions 32. In this manner, the shoulder andrings are abuttable along mating portions of their curved surfaces,instead of along what is at least initially a line contact in the caseof shoulder 31 of the form of the apparatus shown in Fig. 1.

The blade shank 13a is, in each form of the coupling apparatus of thisinvention, movable axially of the opening .21 in the housing and in adirection away from the rear wall thereof by a means which acts totransmit force between the housing and the blade shank concentrically,of the axis of the opening. In this manner, as in my earlier copendingapplication, the blade may be rotated within the opening of the housingto a predetermined pitch and then moved into abutment with the retainerelement without disturbing the predetermined pitch. For this purpose,there are provided a plurality of jack screws 38 which are carried byand extended through the rear wall 4 20 of the housing for engagement attheir inner ends with the end of the blade shank and for manipulation attheir outer ends exteriorly of the'housing within the space between thehousing and hub provided by spacer 25. It will be understood that whenarranged concentrically of the axis of the opening 21 in the housing andthe means for attaching the housing to the hub 10, the jack screws maybe rotated to transmit force between the housing and the blade shank ina direction concentrically of the opening, so that there is no tendencyfor the predetermined pitch of the blade to be disturbed. Thisarrangement of the jack screws 38 also permits one or more of them to betightened to a greater extent than one or more of the others so that theblade may be adjusted to bring its center of gravity into or towardaxial alignment with the housing opening, it such adjustment isrequired.

It is contemplated that with the blade 13 molded into the hollow shapeindicated in the drawings, the centrally disposed means for attachingthe clamp to the hub may project within the open end of the blade shank.Also, when fabricated of a relatively soft material, such as plastic,the ends of the blade shanks may include a bearing part in the form ofan annular metallic plate 39 so positioned on the end of the plasticportion of the blade shank as to be engaged by the inner ends of thejack screws 38. As indicated in Figs. 2 and 3, the annular plate 39 maybe provided with suitable projections 40 receivable in complementaryrecesses of the plastic portion of the blade shanks 13a for aligning theplate 39 with respect thereto. Obviously, a suitable adhesive materialmay be used for cementing the plate to the plastic portion of the bladeshank. I

The form of the coupling apparatus of this invention shown in Fig. 4illustrates another means by which the housing of the clamp may beconnected to a hub. In this case, a rod 41 extending radially outwardlyfrom the hub (not shown) may be threaded at its outer end for connectionwith a threaded opening 42 through the rear wall 43 of the housing andlocked with respect there to by a nut 44 bearing upon a washer againstthe inside of the rear wall 43. In this form, as in the form of Fig. 6,the open end of the plastic portion of the blade shank may be closed bya plug 45 of any suitable material which provides a balance for theblade and is recessed at 46 to accommodate a projecting portion of themeans of attaching the housing to the hub. Also, in these forms of thecoupling apparatus, the inner ends of jack screws 38 bear upon anannular metallic plate 47 secured to the ends of the plastic portion ofthe blade and the plug.

Further, as shown in each of the forms of Figs. 4 and 6, the jack screws38 include a lock nut 48 received about the threaded length thereof andadapted to be made up against the outside of the rear wall of thehousing for fixedly locating the jack screws and preventing the screwsfrom being accidentally backed 01f or retracted from engagement with theend of the blade shank.

Although the manner of using the coupling apparatus of the presentinvention is believed apparent from the foregoing description, it willbe assumed, for purposes of summary, that a fan blade 13 is to becoupled to the hub 10. In such a case, the jack screws 38 are backed offand the retainer element portions 32 are removed from within the housingso that the fan blade may be lifted into a tilted position and movedclear of the fan ring 12 to insert the shank 13a into the housingopening. With the blade so disposed, a first of the retainer elementportions may be moved through the annular space between the housingopening and the blade shank and forced into the groove 30 by means of asuitable tool. It may be found necessary to hold the blade in a slightlytilted position away from the portion of the groove for receiving theretainer element. At any rate, the second or succeeding retainer elementportions are then moved through the annular space and forced into thegroove 30, wherein they are disposed in circumferentially spaced apartrelation with respect to one another.

At this time, or for that matter during insertion of the blade shankinto the housing opening, the blade may be rotated to the desired pitch.The jack screws 38 are then manipulated from a position exteriorly ofthe housing so as to move the shoulder on the blade shank tightly intoabutment with the retainer element. Although the jack screws may requireindividual and successive tightening, their concentric arrangementmaintains the predetermined pitch of the blade as the shank shoulder ismoved into abutment with the retainer element.

If it is desired to adjust the pitch of the blade, the jack screws 38need only be backed otf an amount sufficient to free the shoulder fromits tight engagement with the retainer element, and the blade rotated tothe new pitch. As described above, the blade shank may then be movedback into a position in which it is held against rotation, Withoutdisturbing the predetermined pitch to which it has just been rotated.

The fan blade 13 may be uncoupled from the hub 16 by a reversal of theabove procedure. That is, the jack screws 38 may be backed off and theretainer element portions 32 removed from within the housing. Thispermits the blade to be tilted to such a position that its tip end isfree of the fan ring 12, and wherein its tapered shank portion permitsit to be moved outwardly of the housing opening.

From the foregoing it will be seen that this invention is one welladapted to attain all of the ends and objects hereinabove set forth,together with other advantages which are obvious and which are inherentto the apparatus.

It will be understood that certain features and subcombinations are ofutility and may be employed without reference to other features andsubcombinations. This is contemplated by and is within the scope of theclaims.

As many possible embodiments may be made of the invention withoutdeparting from the scope thereof, it is to be understood that all matterherein set forth or shown in the accompanying drawings is to beinterpreted as illustrative and not in a limiting sense.

The invention having been described, What is claimed is:

1. Apparatus coupling a fan blade to a hub, comprising a housing havinga rear wall and a cylindrical opening therein opposite the rear wall, ashank on the blade received within the opening and having a shou1derthereabout facing away from the rear wall of the housing, a

groove about the periphery of the opening, a retainer element within thegroove and having parts projecting radially inwardly of the housingopening, and force transmitting means operable between said wall andblade shank to move said shoulder into fixed engagement with saidretainer element parts and the end of the shank being spaced from thewall to permit its retraction out of fixed engagement therewith, theshank and opening providing an annular space therebetween when saidshoulder is retracted to permit said retainer element to be insertedwithin and removed from said groove through the end of said opening whensaid shoulder is retracted.

2. Apparatus of the character defined in claim 1 where in a portion ofthe blade shank intermediate the shoulder and end thereof is taperedconvergently toward said end to permit the shank to be tilted withrespect to the axis or the housing opening during insertion or removalthereot.

3. Apparatus of the character defined in claim 1, wherein said forcetransmitting means comprises jack screw means carried by and extendingthrough the rear wall of the housing for engagement with the blade shankand manipulation from the exterior of the housing.

4. Apparatus of the character defined in claim 3, where in the rear wallof the housing has a part disposed axially of the opening therein forattachment to the hub, and said jack screw means comprises a pluralityof jack screws arranged concentrically of said attaching part.

5. Apparatus of the character defined in claim 1, wherein said retainerelement comprises separate portions curved about an axis concentric withthe housing opening disposable within the groove in circumferentiallyspaced apart relation.

6. Apparatus of the character defined in claim 5, wherein the retainerelement portions are circular in cross section and the groove isarcuate.

7. Apparatus of the character defined in claim 5, wherein the retainerelement portions are tapered convergently toward the end of the housingopening for abutment with a similarly tapered surface on the blade shankshoulder.

References Cited in the file of this patent UNITED STATES PATENTS

